This application claims the priority benefit of European Patent Application No. 01107650.2, filed on Mar. 28, 2001, and entitled xe2x80x9cClamping Device for Removable Disks.xe2x80x9d
1. Technical Field
The present invention relates to clamping devices for supporting and releasing recording media disk, and in particular to spindle clamps for removably supporting a disk for rotation about an axis, where the disk has a central aperture.
2. Description of the Prior Art
Disks need to be tested after their manufacturing. Normally this will be done in so called test drives. Placement of disks on test drives involves three aspects: disk introduction, centering, and clamping. U.S. Pat. Nos. 4,755,981, 5,048,005, and 5,056,082 mainly address clamping of the disk in the test drive.
U.S. Pat. No. 4,755,981 discloses a clamp device in which fluid pressure actuates release of a disk and split jaws engage the aperture edge of the disk to clamp the disk in absence of fluid pressure. The clamp device comprises a hub which is rotatable about a central axis, an annular jaw split into a plurality of jaw pieces and disposed in a trough defined in the top end surface of the hub, a cap in contact with the jaw pieces with means for biasing the cap downward against the jaw pieces and means for applying fluid pressure to force the jaw pieces upward. A portion of the hub forms a central cone radially inward from the trough, the surface of the cone defining a wedge surface. O-ring springs are provided for biasing the jaw pieces inward into engagement with the wedge surface. In absence of fluid pressure, the cap forces the jaw pieces downwardly and the wedge surface forces the jaw pieces outwardly into engagement with the a disk. Fluid pressure is applied through passageways in the hub to a diaphragm in the bottom of the trough. The diaphragm bulges upwardly forcing the jaw pieces on the top of the diaphragm upwardly. The O-ring springs maintain the jaw pieces in engagement with the wedge surface, thereby forcing the jaw pieces inwardly, releasing the disk.
U.S. Pat. No. 5,048,005 discloses a clamping apparatus which includes the lock member and the hub. The hub is adapted to be mounted to a conventional spindle, which spindle defines a rotational axis for the hub. The hub has an axial frustroconically-shaped upper portion and a disk-seating surface proximate to the base of the upper portion. The lock member is a unitary, cup-shaped member made of an elastically flexible material and preferably includes a plurality of axially-arranged fingers. Pneumatic or mechanical actuation of a piston within the hub is translated to the lock member to cause movement from a disk-releasing position to a disk-clamping position. Downward movement of the piston draws the lower extremities of the fingers along the bearing surface of the hub until the lock member reaches the disk-clamping position in which the fingers press a data disk against the disk-seating surface of the hub. A spring is utilized to bias the lock member in the disk-clamping position.
U.S. Pat. No. 5,056,082 discloses a spindle clamp for removably supporting a data disk wherein the clamp has a spindle adapted for rotation about a vertical axis. The top of the spindle is stepped, having an inner raised surface, an intermediate gap-forming surface and an outer disk-seating surface. A segmented annular jaw assembly rests atop the raised surface and forms an annulus having an outer diameter less than the inside diameter of the data disk. The radially inward portion of the jaw assembly has an inverted and truncated conical bearing surface in frictional contact with a conforming wedge surface of a cam member. Downward displacement of the cam member causes the wedge surface to move the individual segments of the jaw assembly in a radially outward direction. The cam member is moved pneumatically from a disk-releasing position to a lower disk-clamping position that positions the edges of the individual segments of the jaw assembly above the data disk. Simultaneously, the cam member contacts a portion of a load transfer member spatially situated between the cam member and the jaw assembly. Interaction of the cam member, the load transfer member and the jaw assembly forces the jaw assembly onto the upper surface of the data disk, thereby securing the data disk to the spindle.
The flexible lock member in both patents (U.S. Pat. Nos. 4,755,981, 5,048,005) having an axially-arranged conical aperture allowing gliding of the lock member over an axially conically-shaped upper portion arranged in the hub causing a movement from the disk-releasing position to a disk clamping position. As well as described in patent U.S. Pat. No. 5,056,082, a conical wedge surface of an axially arranged cam member is gliding into the conical bearing surface of the segmented annular jaw assembly.
Another disadvantage is, as described in patent U.S. Pat. Nos. 4,755,981 and 5,056,082, that the surface of the disk can be damaged because of radial sliding segments or a cup shaped member while clamping. The manufacturing of the conical aperture as well as the conically-shaped upper portion has to be made with high precision resulting in a high technical expenditure. Furthermore, the segmentation of the lock member is made with displaced arranged holes and cuts which are very costly and time consuming. Clamping of disks can be negatively effected by adversely arranged positions between the conically-shaped upper portion and the conical aperture of lock member resulting in negative effects with testing of disks. Finally, clamping is restricted to vertical usage only due to movably-arranged lock member.
It is therefore object of the present invention to provide a clamping device avoiding the disadvantages of the above mentioned prior art. This object has been solved by the features of the independent claims. Further preferred embodiments of the present invention are laid down in the dependent claims.
One embodiment of the present invention discloses a clamping device for clamping of disks. The clamping device comprises a flexible lock member, a hub in which the lock member is arranged and a cap. The hub is adapted to be mounted to a conventional spindle, which defines a rotational axis for the hub. The upper portion or middle portion of the hub having a recess including a guiding portion preferably cylindrical in axial direction in which the lock member has to be axially introduced. A clamping effect between lock member and recess is preferably achieved by selecting outer diameter of the lower portion of the lock member greater than the diameter of the cylindrical recess. Furthermore, the hub has a disk seating surface proximate to the base of the upper portion. The lock member is an unitary cap-shaped member made of elastically flexible material at least in its upper part and preferably includes a plurality of axially-arranged fingers. The fingers preferably comprises a lower and an upper portion. The lower portion comprises an outer stiffening area forming a greater diameter than the upper portion. The stiffening area involves two aspectsxe2x80x94clamping of the lock member within the recess of the hub and avoiding bending of the axially-arranged fingers in their upper portion during the disk clamping position. The fingers at least in their upper portions are arranged in an inclined position providing a secure clamping effect. The outer border of the cap contacting the fingers is conically-shaped. Pneumatic or mechanical actuation of a piston within the hub is translated to the lock member to cause movement from a disk-releasing position to a disk-clamping position. Downward movement of the piston forces the conically-shaped outer border of the cap against the rounded outer fingers thereby causing an expansion of the outer fingers until the outer fingers reach a disk-clamping position in which the outer fingers press a disk against the disk-seating surface of the hub. A spring is utilized to bias the lock member in the disk-clamping position.